Audio grip force indicator



0ct. l4, 1958 VAN KREVELEN 2,855,778

AUDIO GRIP FORCE INDICATOR Filed July 26, 1954 1% WORK Plea? U Paws '-*38 Gave-Aura? i i i i o OSCILLATOR T T I 4a 5: I I

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fan M0 A? l A/v MEI am BY JMRBMM Arramver United States Patent a ti 2,855,778 AUDIO GRIP FORCE INDICATOR Edward R. Van Krevelen, Robbinsdale, Minn., assignor i to General Mills, Inc., a corporation of Delaware Application July 2e, 1954, Serial No. 445,698

7 Claims. (Cl. 73-441 y This invention relates in general to signaling systems and pertains more particularly to an audio grip force indicator for signifying to an operator the degree or magnitude of pressure being applied to an objectheld between two relatively movable clamping members.

The instant invention will find especial utility in re- 7 mote control handling units such as that disclosed in the chanically applied to breakable article so that he may always exercise the proper degree of control over the equipment.

Since the operator has no feel over the work being handled, there being a total absence of personal contact, resort has been made to visual indicators. However, these visual indicators have been grossly inadequate, mainly due to the fact that the operators attention must be devoted to the watching of what the equipment is doing without having to shift his gaze to some instrument not always precisely in his line of sight. In order to obviate the foregoing difficulty encountered with visual indicators, an object of the present invention is to provide an audible force indicator that will be practical, reliable and satisfactory in its operation.

Another object of the invention is to provide an audible indicator of the above described character that will produce readily distinguishable sounds for the different degrees of applied pressure. More specifically, the invention envisages the utilization of a substantially constant tone which is blanked out or interrupted at various successive intervals, the duration of each interruption depending upon the magnitude of force applied to the work article at that particular moment. In this way, the operator is constantly apprised of the work pressure, and such pressure can instantly be moderated as circumstances dictate.

The invention also takes cognizance of the fact that the human ear is susceptible to irritation when subjected to a continuing sound of the same pitch over a pro longed period. With this in mind, provision is made for selectively varying the pitch so that whenever a particular pitch becomes objectionable it may be changed to one of a different frequency, thus giving the operator tonal relief.

Other objects will be in part obvious, and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application which will be indicated in the appended claims.

In the drawing:

Figure 1 is a diagrammatic representation of an audible force indicator forming the subject matter of the present invention;

Fig. 2 illustrates a curve indicative of pulses produced during the application of a relatively low force; and

Fig. 3 is a view similar to Fig. 2 but depicting the application of a relatively high gripping force.

In order to render the description of the invention as simple as possible the details have been only schematically portrayed. By referring to Fig. 1, it will be seen that there is employed a driving motor designated by the numeral 10, having an armature 12 and a field 14. By reversing the field 14 relative to the armature 12 it will be appreciated that the motor 10 may be operated in either direction. Connected to the armature 12 is a drive shaft 16 having at its free end a pinion gear 18. The larger gear 20 has in threaded engagement therewith a screw shaft 22 carrying at one end a clamping jaw member 24. When the motor 10 is energized, it will be recognized that the screw shaft 22 is moved axially with respect to the gear 20 and in this way positions the clamping jaw member 24. Another jaw member 26 is mounted for cooperation with the jaw member 24. This jaw member 26 is resiliently biased toward the member 24 by reason of a coil spring 28 having one end fixedly anchored at 30. Gripped between the jaw members 24 and 26 is a work piece bearing the numeral 32 which may be any article that is to be handled. Since the invention is primarily concerned with the handling of fragile or frangible material, it can be assumed that the work piece 32 illustrates an article of glass or the like.

Carried by the jaw member 26 so as to be movable therewith is a wiper or brush 34 which slides over a resistor 36. By so arranging the parts it will be recognized that the resistance is modified due to the action of the wiper 34 moving in association therewith and that any movement of the wiper 34 will be'dependent upon the clamping pressure exerted by the jaw members 24 and 26. It might be pointed out at this time that the coil spring 28 need not possess linear characteristics for the spring may be made non-linear so that greater deflection may be realized with comparatively small forces. Also, in this connection, it will be appreciated that the resistor 36 might possess non-linear characteristics for the same reason.

The variable resistor 36 is connected with the frequency determining circuit of a relatively low frequency pulse generator 38 indicated for the sake of simplicity by a block diagram. The output from the pulse generator 38 which is of course influenced by the position of the wiper 34 is fed to an audio oscillator 40 which is normally arranged to provide a musical tone of constant pitch. The purpose of the pulse generator, the output of which has been already mentioned as being dependent upon the position of the wiper 34, is to interrupt at intervals the output from the audio oscillator so that the tone emitted by loud speaker 42 is of an intermittent character.

To illustrate better the roles played by the pulse generator and the audio oscillator, reference should now be had to Fig. 2 where the output from the loud speaker 42 is presented, this particular figure dealing with the output I for a relatively low gripping pressure exerted by the jaw members 24 and 26 against the work piece 32. In order to produce the tonal output of Fig. 2, which pulses bear the numeral 44, and which pulses 44 are of a repetitive nature, the output of the pulse generator 38 fed to the audio oscillator 40 literally blocks out those pulses which would normally occur in between the various groups of pulses 44 pictured in Fig. 2. Thus it will be discerned that the human ear will experience a relatively long period of silence between the various groups of pulses 44 and that his ill give he -operat r an. indication hat. o ly, a relatively smalla-mouut of gripping force is being applied to the work piece 32. However, whenltheforce; orpthe ork pie e- 2. been increased, then h p lse. generator 38, doesnot blochout asmany of: the pulses producing the output tone from the speaker 42 and theseseries of pulses have been disinguished. in Fig, 3.fromthose of Fig. 2 by theutilization of referencenumeral 46. While any preferred gap .may-Jbe. used, in order to distinguish between a relatively great gripping pressure andacornpa ati ely ma l amount ofgr ppins orce, will erved hat v nv ig-v e a dible pulses occu hr e time e as .freguently as those. of Fig, 2. For -intermediate pres sur s he Per ods of, int rrup on will, v sabe of dnrations in between those shown in Figs. 2 and'3.

Quite obviously the volume of theoutput pulses 44 I and 46 must be. controlled and in order toaehieve this end, theinvention contemplates the employment of avolume control designated by the reference numeral 48. Also it hasbeen recognized from-actual experience that when the human ear encounters the same tonal pitch for aprolonged length of. time the ear is apt to be irritated. With this in view it is within the contemplation of the invention to, utilizea plurality of condensers 5th, 52, 54, and 56, each connected to a terminal which ispart of a selector switch designated generally by the reference numeral 58. Therefore by merely adjusting the selector switch 58 so that the switch arm there-of is in circuit witha particular condenser 50, 52, 54, or 56, the frequency determining circuit of the audio oscillator 50 is changed so that a somewhat different pitch emanates from the loud speaker 42. In this way the operator may select whatever pitch is most pleasant to his ear and after this pitchhas become monotonous may readily modify it so that a different pitch is received via the speaker 42.

From the preceding description .it is felt that the operation of the system constituting the audio force indicator is perfectly obvious. However, a brief review thereof will now be given. When the operator energizes the motor to exert a force against the work piece 32 by means of a screw shaft 22 and the intermediate gears 18 andlfi, the spring 23 will 'beelongated andpermits the wiper 3410 move. over the resistor 36 inasmuch asthewiper 34 is mountedon the iaw member 26. This action results in a frequency. change of the pulse generator 38, which changeis fedto,,the audio oscillator 40. Since the audio oscillator, is normally putting out a relatively constant pitch tone by way of the loud speaker 42, the outputfrom the pulsegenerator 33 which is fed to the audio oscillator 41} modifies this output, creating actual gaps orspaces in the tonaloutput from the speaker 42. These gaps are apparent from an inspection and comparison of Figs. 2 and 3. As already indicated, the pulses of Fig. 2 are indicative of the application of a relatively low clamping action againstthe work piece ,32 whereas the pulses of Fig. 3 are of arelatively high degree of clamping action.

As many changes could ,be made. in the above construction and many apparently widely different embodiments of thisinventionlcould be made without departing from thescope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

it is also to be understood that the language used in the following claims is'intended to cover all of the generic and specific featuresyof the invention herein described all statements of the scope of the invention which, as a matter of language, might be said to fall thereetween.

1.; In:- om ination with pair; of. r l tiv ly movable work clamping members, an audio grip force-indicator comprising sound producing means, means for producing a tone from said sound means having a given pitch, and means actuated by one of said clamping members for completely interrupting said tone at intervals which are variable in accordance with the force exerted by said clamping members against an object held therebetween.

2. In combination with a pair of relatively movable work clamping members, an audio grip force indicator comprising a loud speaker, audio oscillator means; for producing a relatively constant pitchtone from said. loud speaker, a low frequency pulse generator in circuit with said audio oscillator means for interrupting saidtone at variable intervals, and variable resistance means actuated by one of said clamping members for controlling said pulse generator to vary said intervals in accordance with the force exerted by said clamping members against an object held therebetween.

3. A combination inaccordancewith claim 2 in which the pulse generator is of a character so that the intervals of interruption are longer for lesser degrees of force application.

4. In combination with a pair of relatively movable clamping jaws, one of which jaws is powered by; an electric motor and the other of which is biasedtoward said one jawby reason of aspring means, an audio grip force indicator comprising a loud speaker, audio oscillator means for producing a relatively constant pitch tone from said loud speaker, 21 low frequency pulse generator in circuit with said audio oscillator means for producing a pulse capable of stopping the audio oscillator means, variableresistance means actuated by said other jaw for varying the frequency of the pulses produced by said pulse generator in accordance with the force exertedrby said jaws against an object held therebetween, whereby repetitive periods of interruption are effected in said speaker tone dependent upon the degree of saidexerted force.

5. In combinationwith a pair of relatively movable work clamping members, an audio grip force indicator comprising a loud speaker, audio oscillator means. for producing a relatively constant pitch tone fromsaidloud speaker, ,includingimpedance means .for selectively vary: ing the pitch of said toneto one preferred by the listener,

a low frequency pulse generatorin-circuit with said audio oscillator means for interrupting-said tone at .variablcintervals, and variable resistance. means actuatedby 'one of said clamping members for controlliug saidpulse generv ator to vary said intervals in accordance with the. force exerted by said clamping members against an object held therebetween 6. Acombination in accordnace with claim5-in which said impedance. means comprises a plurality of condensers each of a capacity to provide a different pitch tone by said audio oscillator means, and switch means for selecting anyone ofsaid condensers to produce a preferred tone.

7. In combination witha pair of relatively movable work clamping members, an audio grip force indicator comprising sound producing means having a givenpitch, means for completely interrupting said tone to produce alternate periods of sound and silence, and meansactuated by one, of said clamping members for varying the number of said periods during a given interval in accordance with the force exerted by said clamping members against an object held therebetween- References Cited in the file of this patent UNITED STATES PATENTS 1,912,213 Ni'colson May 30, 1933 1,946,774 Wilms Feb. 13, 1934 2,383,321 Kleber Aug. 21, 1945 2,626,522 Brown Jan. 27, 1953 

